Sprocket enclosing system



{19,1953 H. N. FAIRBANKS SPROCKET ENCLOSING SYSTEM 3 Sheets-Sheet 1 Filed Nov. 1. 1950 J p; g y I [I I attorneys 'May 19, 1953 H. N. FAIRBANKS SPROCKET ENCLOSING SYSTEM 3 Sheets-Sheet 2 Filed Nov. 1, 1950 I FIG.4.

HENRY N. FAIRQANKS nventor (Bl-omega Patented May 19, 1953 SPROCKET ENCLOSING SYSTEM Henry N. Fairbanks, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application November 1, 1950, Serial No. 193,395 18 Claims. (01. 27'1 2.3)

The present invention relates to a motion picture apparatus, and more particularly to a system for enclosing a film feeding or hold-back sprocket. The system, in its broadest aspects, comprises a dual housing which encloses the sprocket and also provides all the guiding and stripping means for th film strip.

The principal object of the invention is the provision of a simple and effective enclosure guid system for a film sprocket.

A further object of the invention is the incorporation of suitable film guides and strippers in the guard system to insure proper feeding and stripping of the film.

A still further object of the invention is the provision of an enclosure system which effectively retains the film in positive contact with the sprocket without the use of holding members, as is commonly required.

Yet another object of the invention is the provision of a system of the class described which is attractive, permits easy threading, relatively inexpensive to manufacture, embodies no moving parts, and is highly effective in use.

To these and other ends, the invention resides in certain improvements and combinations v of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Fig. 1 is a front elevation View of one embodiment of a sprocket enclosing system constructed in accordance with the present invention;

Fig. 2 is a vertical, sectional view taken through the system illustrated in Fig. 1, showing the relation of the system to the film sprocket;

Fig. 3 is a diagrammatic view showing the relation of the enclosing sprocket system, shown in Fig. 1, arranged in the film path of a motion pic ture apparatus, such as a projector;

Fig. 4 is a broken away end view of a sprocket enclosing system constructed in accordance with another embodiment of the invention, showing the relation of the parts of the system to the film sprocket; I

Fig. 5 is a vertical, sectional view taken substantially on line 55 of Fig. 4, showing the relation of the system parts of Fig. 4 to the sprocket and its supporting shaft;

Fig. 6 is a perspective exploded view of the two housing or enclosing members of the sprocket enclosing system illustrated in Figs. 4 and 5;

Fig. 7 is a diagrammatic view, showing the position of. the sprocket enclosing system of Figs. 4-6 in connection with the film path of a motion picture apparatus such as a projector;

Fig. 8 is an end elevation view of still another embodimentof a sprocket enclosing system constructed in accordance with the present invention;

Fig. 9 is a vertical sectional view of the systern-illustrated in Fig. 8 taken substantially on line 9-9 thereof showing the relation of the sprocket and its supporting shaft thereto; and

Fig. 10 is a horizontal sectional view taken substantially on line I0--I0 of Fig. 8 showing the relation of the system to the sprocket, and the arrangement for connecting the system parts and for mounting the system on the base plate or mechanism housing sprocket boss.

Similar reference numerals throughout the various views indicate the same parts.

Figs. 1-3 show one form of a sprocket enclosing system constructed in accordance with the present invention. As the invention relates to the sprocket enclosing system, only so much of the projector is shown as relates to the system. The other projector parts may be of any suitable or well known construction, and do not. constitute a part of the present invention. Accordingly, these other projector parts are not shown or described.

Referring now to Fig. 2, there is shown a base plate or mechanism housing sprocket boss II to which the enclosing system is mounted. The plate II is formed with an aperture I2 through which thesprocket shaft I3 extends. An inner sprocket 'housing, broadly designated by the numeral I4, is provided with a flat, radially extending plate portion I5, which overlies the base II, see Fig. 2. The portion I5 is provided with an opening I6 in registry with the opening I2 to receive shaft I3. The housing I4 is positioned, as shown in Fig. 2, against the plate II. A thrust washer I'l, sprocket hub I8 and sprocket I 9 are then assembled on the free or left end of shaft I3, the latter bring spring loaded to the right, in a manner well known in the art. A screw 20 then serves to retain the assembled parts on the shaft I3 and to hold the plate I5 in contact with the base I I, all as clearly shown in Fig. 2. As the sprocket and hub assembly do not form, per se, a part of the present invention, further details are not shown or illustrated. It is apparent that the above-described assembly serves to retain the plate I5 of the inner housing I4 in tight engagement with the base plate I I, as is apparent from an inspection of Fig. 2. The inner housing I4 is also provided with an axially extending arcuately shaped portion 2| which extends over and covers the upper portion of the sprocket assembly, as shown in Figs. 1 and 2. A1-

, thesprocket assembly. "The top edge 3!, of plate 20 plate ll.

2,639,147 3 4 though the inner housing sprocket I4 is now advantages of which are deemed apparent. Thus, held against the sprocket base or base plate II the film is guided both vertically and laterally. by the hub assembly, it is free to rotate and trans- As the trailing end of the film approaches the late for the final orientation with respect to the exit 28, said end may tend to be picked up by and sprocket l9. 5 fed under the sprocket. In order to overcome An outer sprocket housing broadly designated such a possibility the arcuate portion 26 is proby the ,numeral'25; isIOrmed Withanaxially ex- .vided... with an inwardly extending lug or surface tending arcuate portion 26 which" overlies the 'lliipositioned adjacentthe sprocket l9 and adbottom portion of the sprocket assembl to co jacent the film exit 28. This lug serves to strip operate with the portion 2! to enclose the sprocket 10 -the trailing end of the film from the sprocket to circumferentially. The adjacent edges of porpermit said end to pass over guide 39 and through tions 2| and 26 are spaced at substantiallyiadiw vihe rexitopening 28. The outer housing 25 is lometrically opposite points. to provide.,film, inlet ..cated positively with respect to inner housing l4 opening 21 and the film exit opening!!! .tqipermit i'..by.,n,ieans .of ,ai projecting tongue 46 formed on the film strip 29 to be fed to and from the sprocket. the plate '1 Sand extending into and registering as is deemed apparent. The outer housing is opening 47 formed on part 26, see Fig. 2. The also formed with a radia1ly-extending end plate two -housings' are fthen anchored to the plate ll 30 formed integral with the portion,25-.apd..co- ,by-ineans of screws 48 which pass through ears operating with the latter. and portion 2| to enclose 49 on portion 26 and..then through plate I5 to "'30 is, curved andis concentric with andslightly 4'-'I-showa-modi-fied sprocket -enclosing spafied from inner edge 32 ofportion 2| to provide system in wh-ich theinner" sprocket housing -is a narrow arcuate slot33 through which'the film formed-toprovide a cylindrical'membei fii posistrip ,m ay be inserted laterally to engagejthe tioned betweenthe sprocketassembly, which may sprocket i9. 25' be of the type above described, and the base-plate When the film 29 is being fed from supply reel l I. The'member- 55 is formed with a central-axial 35 an d .over. 1the upper-film sprocket, seeiFig; p n n 6 hroughwhich the Sp Sha t-l3 tojthefilm gateitfi, the'filnrtravels approximately extends. '-'T-he--member 55 is provided with an through a pathA-a-Afl figil, over the"upp,e1 por- "overhanging axially extending ring fil-which over- 1 tion of the sprocket. 1 However; When'the' film 30 lies the sprocket assembly, ashestshownin'FigpS. passes' from. gate 86' to the loweror take-up reel The'member-SE may be: anchored orfixed to the 111, ;it, passes,approximately'through a patl'r-B- B, plate 1 I in anysuitahlemanner such,-for-example, Fig. 1, over the upper portion-of the: lower by screws 58. The-'outer sprocket housing is in sprocket. 'llhuathe exactdirection of travelover the form of a tubular member 59 -whicha'slides "the sprocket depends upon'the'relaticn ofthe 35-=-over portion- 55 in telescoping relation. Ashoulsprocket ,to the" film. However,"bothppper; and rior-"60 formed-on the inner surface ofthe'member lower. sprocket assemblies and their en'closingsys- "53 engages the-edge 6 l of ring-51 to position :the toms, therefore, are. 'identicaldn structure. "In 'member ifl on- -portion 55. "The -outer housing is both cases thefilrn passes only overthe upper porformed with an integral end plate 6 i whi'ch overtion of the sprocket, as clearly shown inffigs. 1 40lies the end-of the sprocket tocomplete the enand3. "When the system is used as a drive closure thereof. An arcuate slot'62 is formed in sprocket, suchasthe'upper sprockeVFig. 3; the plate 6| to permit lateral insertion 'of' the'film incomi ngfilm contacts a vertical" film guide surstrip so that the latter may be'moved into engage- 'IfiQG38'fOI'IIl8d at the right edge of the portion mentwith the'sprooket.

2|. The guided-film then engages-sprocket-H, In---0rder't0 prevent-rotation of the outer housand, on leaving the, s stem, contacts th vertical ---ing--relative= to theinner housing a-spline con- ,guidejfl. formedatthe left edge ofithe portionzl, -nection is-provided therebetween. To this end,

Fi l,.th,us.the, a .'cuate .portion-2|, serves to 'theouter f ce-M i the inner member 55. is guidethe'film to and from the sprocketpwhenthe provided--with-a :plurality of radially extending latter is used as an upper, orydrive sprocket. lugs 64, in the present instance three. The inner When,. h th filmpasses' to the" lower surface-'65 of the portion 59 is formed with simiyee1 3], it engagesthe 'guide surfage'lfl formedon larlyshaped slots 01 groovesfifi to receive the lugs {the left end of portion26 adjacent-the exit open- 64. Thisconstruction-permits free axial sliding i ng;28,:t he n to theguide surface.',39,and finauy -of the-portion59 on member yet effectively t th sp igcket is, Th gurfaoe'jfljig carefully prevents -re1ative rotation thereon. To insure voriented with respect to thesurfacegflto insure p per. assembly f the h n e l 64 nd ,proper feeding of thefilm fromthe lowerjilm igrcoves 65 are not all of equal width so that the .loop to thelower sprocket. \"Ihe film feeds off the part ,59 can-be assembled on e portion 55 y -.lowersprocketover the surface 38.01: guide sur- "in one definite relative position. The portion 59 Jam e hformedon portionzfiadjacent the inlet .60 is held placeby a Snap ring 57 having a D pening !m nd.i herwe..t0...thc,takezupreelj3'1. .rality of flexible fingers 68 which engage in .The.partioularcsurfaiieifl Ol.4l. contacted byfgthe notches 69 formed on the outer surface of the .m i th 1 gnclqsjng systgm.dgpends I portion59. Thus, the two housing members are ,'.upon the diameter .of ,the film-on .the ,reeli-3l. retained in pr p r led lation.

.,Thu s,,.the,guide, surfaces 38.'39, 40.and.4!,,,pro- '65 Theportion 59 is provided with a film inlet 10 .yide yertical guideseforflthe,incoming.and leaving and afilm outlet ll so that the film strip may .filpi.st rips and insures, positive.engagementoflthe befed to. and from the sprocket. The film is .istripwith the sprocket. "guided laterally by means 3 of shoulders formed lnrthe. courseof its travel over-.the. sprocket, ,on the. sprocket hub, as shown in Fig. 5, rather =the marginal edgesA2-of'the fi1m.st1ip.29 engage 70 ,than by means of. lateral guides on the inner the, .-inner surface-.43..of..p1ate.l5.,and.,the inner and.outer' housings, as inthe arrangement in surfaceA lrof.platefiflto provide lateralguides for .Eigs.-.13. .Howevenin both cases lateralguid- ,the.film-so as,to insurethatthe marginalperfora- -ing of the. filmisprovided so as to insure proper tions of the filmstrip willbe maintained in lateral scooperation. of the. sprocket. teeth ,with the. film alignment with.- theteeth of thepsprocketplfi the '75 perforations. addition, in ,order to vertically guide the film, the portion 59 is provided'with liplike section or edges 12 which engages the upper surface of the film strip to provide vertical guides for the strip to insure that the latter will be retained in positive engagement with the sprocket. The edges 12 are positioned at inlet and outlet 1 I, as best shown in Figs. a and 6. Thus, the film strip is guided both vertically and laterally during its passage over the sprocket. When the enclosing system is used in connection with the upper or drive sprocket, the system is positioned as shown in Fig. 7 so that the film will be fed over the bottom of the sprocket. However, when used in connection with the lower or hold-back sprocket, the system is reversed so that the film feeds over the top of the sprocket. When the device is used in connection with a silent projector the film follows the path shown in solid lines in Fig. 7. However, the enclosing system is also adapted for use in connection with a sound projector. In such a sound apparatus, the film is fed as shown in dotted lines Fig. 7 from the film gate 36 to and around a sound drum [5 then over an idler roll 16 to the lower sprocket. Obviously when the film follows this latter path it will be rather difiicult to have the film enter the enclosing system through the film inlet 10. Therefore, the portion 59 is provided with an additional or auxiliary film inlet I1 positioned below the inlet 10, as shown'in Fig. '7.

With this arrangement the film may be fed in a straight line from the roller to the lower sprocket, the advantages of which are deemed apparent. This auxiliary inlet 11 is also provided with a vertical film guide (1a. positioned at the auxiliary inlet. Due to the non-uniformity of the lugs 64 and grooves 66, the housing 59 can be assembled on the portion 55 only in a definite relative relation thus assuring the correct positioning of film inlets and film outlets. In order that the film passing through inlet 19 or 11 and the outlet H may engage the sprocket proper, the overhanging ring 51 of the portion 55 is provided with slots Illa, Ila and 11b, arranged in registry with the inlets l0 and T! and the outlet H to provide continuous openings through the enclosure member.

Figs. 8-10 show still another modification of a sprocket enclosing system in which a single sprocket is used both as a drive sprocket and as a hold-back sprocket. In this embodiment, sprocket i9 is mounted directly on the sprocket shaft I3 and is held thereon by a screw 80. The shaft extends through a bushing 8| formed integral with the inner housing which comprises a cylindrical member 82 spaced from andconcentric with bushing 8! but connected thereto by a radial flange or web 83, as shown in Fig. 9. An outer casing 84 surrounds the cylindrical member 82 and is connected thereto by a radial web 85 spaced axially from web 83, or to the left thereof as viewed in Fig. 9. The above described arrangement provides an annular groove 86 around the sprocket to provide the desired dual film paths as shown in Fig. 8. The annular recess 86 communicates with a pair of channels 87 positioned on opposite sides of the sprocket. A sprocket guard plate has a central circular portion 88, and side portions 89 which conform in shape to the channels 81. Studs 90 extend through parts 89 of the cover plate and posts 9! formed on an inner housing, and are threaded into the base plate H or other suitable support to connect both the cover plate and the housing to the base plate, as shown in Fig. 10. The studs 90 not only retain the enclosing parts in position -'of the sprocket, and then leaves through a film outlet 95, the film following the path shown by the lower dotted lines, Fig. 9.

During the passage of the film through the system in either direction, one marginal edge of the film engages the inner surface 96 of a radial guide 91 of the inner housing, while the other marginal edge of the film engages the inner surface 98 of the sprocket guard plate, as shown in Fig. 9 to afford eflfective lateral guiding for the film. The sprocket guard plate closes and outer housings. formed with curved sections 99 which serve to film outlets 93 and 95.

the annular groove 86 and may be broadly considered as an outer housing so that the film may be deemed to be guided laterally by the inner In addition, the web is guide the film vertically in its passage to and from theenclosing system. Such vertical guides are best shown in Fig. 8, and are positioned adjacent the two film inlets 92 and .94 and the two Thus, the film strip is guided both vertically and laterally. The upper and lower edges I80 and I0! of the sprocket guard plate conform to the shape of the edges of the web 95 as shown in Fig. 8, to provide upper and lower film insertion slots I02 and I83 through which the film may be inserted laterally,

and into engagement with the sprocket, as shown in dotted lines I04 of Fig. 9. Thus the film inlets and film outlets or openings, and film insertion slots are provided. In addition, the film strip during its passage through the enclosing system is guided accurately and positively by stationary lateral and vertical guiding members formed on the system itself.

It is apparent from the above description that the present invention provides a sprocket enclosing system which effectively encloses the sprocket, yet assures proper feeding of the film. The latter is retained in contact with the sprocket without the use of commonly employed movable members. The film is guided to and from the sprocket by suitably arranged fixed vertical and lateral guide members or surfaces which insure proper cooperation of the film strip with the sprocket. Theenclosing system of the present system is attractive, easy to thread, low in cost, and free from moving parts.

While certain embodiments of the invention have been disclosed, it is to be understood that the inventive idea may be carried out in a number of ways. Therefore, this application is not to be limited to the precise details disclosed, but is intended to cover all variations and modifications which fall within the scope of the appended claims.

I claim:

1. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket of said sprocket and between said sprocket and mascara? 37 =eaidplate anothertportionibfz:saidahousing:being formed to "provide an? arcuatei-sectiornwhichrextends over at least a partiof saidisproeketaian outer sprocket housing I having atileast a 'portion :8 fi-of' said @spro'cketfi'and"between isaid fsprocketi' and s'aidplate'; another portion 'of' said housing being ,sfornred to provide an arcuate section which lextends over 'atileast I ai part 'of said sprocket, an

i'ith'ereof -o'sit ed w ,iandthe sid ,bf arsaid -f 5 :"oute1:"sp1'ocket liou-singha'ving at least a'portion -sprocketand cooperating with said first housing to --provide' an" enclosed system ":for sai sprocket, said system being fcrrn'ed to provide a film inser- 'tion' slot' and I a film entrance :opening and al film th'ereof .rpositioned on another side of aid sprocket and-cooperatingwith said first housing .wto provide-an 'enclosed system for said'sproclfet, .saidusystem being formed-to provide a film'inser- "ings.

2. In motion picture apparatus, the combi- -nation with a film feeding-sprocket; a I supporting shaft therefor, and abase -plate through whibh said shalt prov ectsg'oi a sprocket enclosing system i comp'rising, "in combination, an inn'er sp'rot zket i housing having a'poi'tion positioned'on one side of said sprocket and-between said sprock'etand s'aid'plate, another portiomof said h'ou'sing 'being exit"opening,.means for-connecting said housings winoperative relation, and means to secure said x-system-wto said platein enclosing relation with r 'saidsprocket.

6. -11'1 a motion: picture apparatus, the oo'mbinatiomwi-th afilm feedingsprocket, a supporting shaft therefoiwand a base plate through which said shaft projects-mtasprocket enclosing system 'cornprising, in combinationfan' inner sprocket 'fiformed in "providgfianza rcuate seQtjbHiWhighzhbx- 3203hous1ng-having31 1301151011positioned on one side 1 tends over at least 1 a part- 0f said-"sprock'ew an outer sprocket housing having at least ai portion *"thereof positioned --on another side of said '-'sp1'ocket--and cooperating with -s'aid mst housing r oi-wsaidrsprocket and I between said sprocket: and said plate, anothen portionof said'housing being formed tto:provide anarcuate -=section= which extendsfiover at least -a' part of said sprocket, an

to provide anenciosed-systenr-ror said=sprocket, 5 outer spr ck t ho n h n at l amort n said' housings-being spaced -to-provide' an arcuate iiim'insertion slot to permitthepositioningbf the -filni-irr 'contactwith said sprocket; i saidhousin'gs also being-provided with a' film entrance "slot 'and ttiiereof wposi-tioned "on "another side .of *said I sprocket and: cooperating-with said first housing to provide an enclosed system for said sprocket,

systembeing forrned'to provide a film inser- "adjacent -sa'1d slots.

3SIn a =m'otionpicture apparatus; 'thecombination with a film feeding sprocketg af-suppo'r ting snare therefor, and a -base plate throiigh which exit opening, and means on-said'system adjacent "said exit opening tostrip the-fihn-strip from said sprocket.

"7x111: a motion -pictm'eapparatus, the combisaid shaft projects, or a-sprocket enclosing system nation wi h a film feeding sprocket, a supp r n comprising, in 'combinttibnpan- 'inner sprocket housing having a'-'portion positioned onone's'ide of said sprocket andpetvveen said' sprocket and said plate,- another-portion =of-s'aid housing being -shaft: therefor; and'a ba'se' plate throughwhich said shaft projects, of a-sprocket enclosing system comprising,"in combination, an 'innersprocket '-housing having a portion-positioned on one side "tendspver "at least a part or said sprocketf'an outer sprocket housing having at least a portion thereof positioned "on another side of 'said sprocket and cooperating w ith said' first housing saidplateranotheri'portionofsaid housing being formed tor-provide an arcu ate -section which extends over -at 'least 'a part of said-sprocket, an outer'isprocket -housing having-at least a portion toprovideamericlosd'systemttor sa'i'd' sprocket," thereof-p On "another S de 0f Said sprocket' and-cooperating:- with said first housing to provide an enclosed systemfor said sprocket, said-system being for-med to provide a film insertion slotra-nd-a film entrance opening and a film -exitopeningpmeans for connecting said housings winoperative relation, means to secure said system -to 'sald-plateand in'enolosing relationwvith said "sprocket, and means on one' of said housings =-adjacent said'- exit-openingto-strip the-film strip eomprlsingp in combination, an inner s'procket p housing having a portion positioned on one' side of sai d sprocket and between said sprocket and said plate;another portion of said housing being formed to provide an=arcuate section which extends over at-least part 'ofsaid 'sprocket, an

outer sprocket housing having at-lezi'st a portion "thereof positioned on another *"side of said sprocket and cooperatingwith s'aid'first' -housing to provide an enc'losed'system for said sprocket,

said system being-formed taprovide a"'fllm= insertion slot and a'film entrance 'operiing -and a film exit opening, lateral film guides on said housings, and vertical film guides formed on said housings adiacent said openings.

"8. 111 a a motion. .picture'apparatus, the combination -with'a' filmfeeding sprocket; a supporting shaft-therefor, :and-a baserplate' through which said-shaft projects 'ofia sprocket enclosing sys- -tem comprising, in combination, an inner 'hsprocket housing having a'portion positioned on one =-side :of said sprocket and between said 'zsprocket and-said plate; another portion of-"said mousing-being formed to provide an arcuate section which extends over atleasta part of said sprocket, an outerfisprocket housing having'at "least a portion thereof: positioned on another side 'of-saidjsprocket and cdoperating'with said first housing to' provide 1 an enclosed system for'said 5.111; amotion-picture apparatus, the combisprocket, 'sai'd systembeing'formed to provide a 1 nation with a film' feeding sprocket, a supporting shaft-therefor, and a base plate through which said shaft projects, ofa sproc'ket enclosingsy'stem ooniprisingfi in combination, an iin'ner --'sprocket housinghaving a lportioni'p'ositioned onf one side 'xfllm 'insertion slot" an'd a film entrance opening and a" film exit-opening," means for connecting z==said housings inoperative relation, means to "se- "cure said system'to saidpla'te'and in'enclosing relation with"saidt spro'cketaandmeans on said 9, bitter housing adjacent said exit opening to strip the film from said sprocket.

9. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having a portion positioned on one side of said sprocket and between said sprocket and said plate, another portion of said housing being formed to provide an arcuate section which extends over at least a part of said sprocket, an outer sprocket housing having at least a portion thereof positioned on another side of said sprocket and cooperating with said first housing to provide an enclosed system for said sprocket, said system being formed to provide a film insertion slot and a film entrance opening and a film exit opening, means for connecting said housings in operative relation, means to secure said system to said plate and in enclosing relation with said sprocket, and lateral and vertical film guides on said housmgs.

10. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having a'radially extending portion positioned between said sprocket and said plate and formed with an opening through which said shaft projects, an axially extending arcuate portion formed on said housing and extending at least part way around said sprocket, an outer housing formed with an axially extending arcuate portion cooperating with the arcuate portion of said first housing to enclose said sprocket substantially circumferentially, and a radial portion formed on said second housing for closing the end of said system.

11. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having radially extending portion positioned between said sprocket and said plate and formed with an opening through which said shaft projects, an axially extending arcuate portion formed on said housing and extending at least part way around said sprocket, an outer housing formed with an axially extending arcuate portion cooperating with the arcuate portion of said first housing to enclose said sprocket substantially circumferentially, and film guides formed on said housings to retain said film in positive engagement with said sprocket.

12. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having radially extending portion positioned between said sprocket and said plate and formed with an opening, through which said shaft projects, an axially extending arcuate portion formed on said housing and extending at least part way around said sprocket, an outer housing formed with an axially extending arcuate portion cooperating with the arcuate portion of said first housing to enclose said sprocket substantially circumferentially, and means to strip the trailing end of the film from said sprocket.

13. In a motion picture apparatus, the combination with a film feeding' sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having radially extending portion positioned between said sprocket and said plate and formed with an opening through which said shaft projects, an axially extending arcuate portion formed on said housing and extending at least part way around said sprocket, an outer housing formed with an axially extending arcuate portion cooperating with the arcuate portion of said first housing to enclose said sprocket substantially circumferentially, means to connect and position said outer housing on said inner housing, and means to attach said system to said plate in enclosing relation with said sprocket.

bination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, a cylin-' drical inner housing having aportion positioned between said sprocket and said plate, and an axially extending annular flange overlying said sprocket, an outer housing having a cylindrical section slidable on said inner housing in a telescoping relation, means on said housings to retain the latter in proper assembled relation, an end plate formed on the end of said section and overlying said sprocket and cooperating with said housings to enclose said sprocket, said outer housing being formed with a film inlet and a film exit to permit the film to be fed to and from said sprocket, and film guides on said housin 15. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, a cylindrical inner housing having a portion positioned between said sprocket and said plate, an axially extending annular flange overlying said sprocket, an outer housing having a cylindrical section slidable on said inner housing in a telescoping relation, means on said housings to retain the latter in proper assembled relation, an end plate formed on the end of said section and overlying said sprocket and cooperating with said housings to enclose said sprocket, said outer housing being formed with a film inlet and a film exit to permit the film to be fed to and fromsaid sprocket, lateral film guides formed on said sprocket, and vertical film guides on one of said housings adjacent said inlet and exit.

16. In a motion picture apparatus, the combination with a film feeding sprocket, a supporting shaft therefor, and a base plate through which said shaft projects, of a sprocket enclosing system comprising, in combination, an inner sprocket housing having a radially extending portion positioned between said sprocket and said plate and formed with an opening through which said shaft projects, and axially extending arcuate portion formed on said housing and extending at least part way around said sprocket, means connected to said inner housing and cooperating therewith to substantially enclose said sprocket, said means being spaced radially from said inner housing to form a film insertion slot and a film inlet opening and a film outlet opening, said openings permitting feedin of the film to and 14. In a motion picture apparatus, the com- 

